Treat .c files as c++

My project uses .c extension for c++ files. I know that's yucky but I can't change it.
I upgraded Qt Creator from 4.0.1., which treated .c as c++ to 4.6.1, which doesn't. Is it possible somehow to treat .c files as c++ in 4.6.1?

Thanks for a quick answer. I don't intend to compile in the Qt creator. 4.0.1 successfully parses my code while 4.6.1. not. I use centos 7 and gcc 4.9.2. I tried to change the compiler to clang 3.8 but that didn't help.

In Qt creator go to "Tools"->Options"->"Build&Run". Under "Compilers" there are typically entries for C and C++ and the actual compiler call is defined. Try to add a new entry for C and use the compiler statement as found under C++. Later you need to make sure that this is used in your toolchain for compilation.

Note: never done this before, therefore, you may have to check that is does work properly.

Open any .c file which contains specific C++ only lines. Lines are not highlighted properly, navigation and refactoring features doesn't work.

Go to Tools->C++->Inspect C++ Code Model
4.1 See two "Project Parts". View both of them.
4.2 One of them has "C11" value at "Language Version" key.

Code model can't be changed using GUI and I din't find any way to manipulate it in other ways (I reviewed Qt Creator configs(...AppData\Roaming\QtProject) and project files (*.creator, *.creator.user).
Tried 4.6.1 and 4.7.0 Beta 1 versions.

If you are positive that this is a bug, you can check always on JIRA for bug report or file one on your own.

Especially when you have found already procedures to verify and show the problem, the best place is JIRA. That is the only place where bug reports are handled properly. The forum here is not monitored for eventual bugs and their reports.